Has there ever been a model (neuro-physical) proposed for the human unconscious brain?
The Unconscious in psychology is related to many aspects of behavior, but many levels of this exist, including low levels (simple tasks) like walking, eating, breathing etc.  This has been investigated in animal world, for example muscular memory, the insect brain model, and Nonlinear System Control Using Neural Networks . Many of these are related to body control.

See also: nested hierarchies of circular emotional control and cognitive regulation for “bottom-up” influences and “top-down” regulations